The broad goal of this project is to better understand mechanisms underlying the effectiveness of behavioral parent-training interventions aimed at child externalizing behavior. More specifically, the present set of studies seeks to accomplish three goals by experimentally manipulating certain parameters of a parent training intervention: First, they attempt to elucidate the role that parental social support plays in the retention, outcome, and maintenance of families who receive parent-training. Second, they seek to examine whether altering the sequence of parent-training topics produces more rapid symptom relief in dysfunctional parenting and whether such immediate improvements reduce parent drop-out and improve outcomes. Third, they seek to examine how gains made in parenting skill and child behavior are maintained after the initial parent-training intervention has ended. Correlational data suggest that rapid symptom relief and robust social support improve the outcomes seen with parent-training interventions. However, there is little experimental evidence to support the contention that these two variables have such effects. It is hypothesized that initial symptom relief and robust social support significantly contribute to retaining parents in treatment and increasing the probability that parents will experience improvements in parenting, and in turn, children will experience corresponding improvement in externalizing behavior. It is further hypothesized that increased post-intervention parent therapist contact will significantly improve the maintenance of gains seen immediately post treatment. This experiment employs random assignment of 120 parent-child dyads seeking treatment for the child's externalizing behavior, to test and examine theory about the role of initial symptom reduction, parental social support, and post-intervention therapist-parent contact on parent-training outcomes. Convincing support for these two relationships could significantly alter the way that parent-training interventions are implemented, leading to increases in the percentages of families who benefit from such interventions.